Skin discolouration in dogs can be as simple as differing natural pigmentation, and as complex as a symptom of disease, parasite infection, or other illness. Some puppies develop different skin pigmentation as they mature. Older dogs experience normal skin colour changes on exposed skin, or on areas that often come into contact with the ground -- such as the leg joints and paw pads.
Most dogs have multi-coloured skin that exhibits many shades of pigmentation. Dogs with coats and skin in shades other than white are considered pigmented. Skin pigments in dogs include purple, dark pink, yellow, black, brown, rust, or red. Dogs with severely darkened natural skin are considered hyper-pigmented. Some individuals of the hairless breeds -- such as the Chinese Crested and Xoloitzcuintle -- exhibit naturally hyper-pigmented skin. Chinese Cresteds vary in coat and skin colour and can also have lighter pigmented skin.
While many medical or genetic conditions can cause changes in pigmentation, the most common causes are hypothyroidism, Cushing's disease, skin cancers, hormonal imbalances, skin abrasions, irritation caused by parasites, allergies, or infection, and irregularities of the skin follicles. Some breeds are predisposed to skin pigment changes as they age that tend not to be harmful. For example, nasal pigmentation changes -- known as Dudley nose -- cause the nose to fade from black to brown or pink. This discolouration is often noted in Labrador retrievers, golden retrievers, and doberman pinschers.
Noticing pigmentation changes
All told there are more than 38 conditions that can cause changes in canine skin or coat pigmentation. Most need veterinary care to resolve. Know what your dog's skin typically looks like and make note of any changes. While most dogs have skin that exhibits different shades across their body, knowing what is normal and reporting any changes to your veterinarian is wise. An early examination can be key in ruling out skin changes of little medical concern. That same examination can give your veterinarian a baseline in the event discolouration continues or the condition requires immediate treatment.